This disclosure relates to a surround for supporting a diaphragm that is used to create acoustic waves. The surround and diaphragm can be part of a passive radiator or acoustic driver.
Passive radiators and acoustic drivers have been traditionally designed with half roll surrounds having a circular or elliptical cross section. Such half roll surrounds are typically made of high durometer materials. This arrangement provides approximate linear force-deflection response until the surround reaches a high strain that results in a non-linear response. In many surround designs, issues of buckling and hoop stresses can result in an unstable dynamic response (like sub harmonic rocking) which is detrimental to the acoustic performance. A challenge in designing a passive radiator is the unstable behavior or non-axial motion of the diaphragm which can occur under dynamic loading. This is largely related to the nonlinear force deflection relationship of the passive radiator which is due to the geometry linearity and material linearity. Instabilities due to nonlinear force-deflection have been avoided by limiting the magnitude of passive radiator excursion, resulting in less acoustic output for a given size passive radiator.
U.S. Pat. No. 7,699,139 discloses a surround for supporting a diaphragm used to create acoustic waves. The surround includes a rib section extending away from the diaphragm and a membrane section that is supported by the rib section. The membrane section has a thickness in a direction substantially normal to opposing top and bottom surfaces of the membrane section which is substantially thinner than a thickness of the rib section in a direction substantially normal to opposing top and bottom surfaces of the rib section. A restoring force returning the diaphragm to a home position is contributed to more due to deformation of the rib section than to deformation of the membrane section.